Introduction:
A cycloconverter is a type of power electronic device that converts the frequency of an AC signal. It is commonly used in applications where variable frequency and voltage control is required. The single-phase mid-point type cycloconverter is a specific configuration of a cycloconverter that can be used to convert single-phase AC power.

Explanation:
In a single-phase mid-point type cycloconverter, the AC input voltage is connected to a pair of SCRs (Silicon Controlled Rectifiers) in an anti-parallel configuration. These SCRs are responsible for controlling the power flow and generating the desired output waveform.

Working of single-phase mid-point type cycloconverter:
The operation of a single-phase mid-point type cycloconverter can be divided into two modes:

1. Positive half-cycle mode: During the positive half-cycle of the input voltage, one of the SCRs is triggered and conducts for the duration of the positive half-cycle. The output voltage is generated during this time and is controlled by the triggering angle of the SCR.

2. Negative half-cycle mode: During the negative half-cycle of the input voltage, the other SCR is triggered and conducts for the duration of the negative half-cycle. The output voltage is generated during this time and is also controlled by the triggering angle of the SCR.

Number of SCRs:
In a single-phase mid-point type cycloconverter, there are two SCRs used in total. Each SCR is responsible for controlling one half-cycle of the input voltage. By triggering the appropriate SCR at the desired angle, the output voltage waveform can be controlled.

Advantages of single-phase mid-point type cycloconverter:
- Provides variable frequency control.
- Can operate with a wide range of input voltages.
- Suitable for applications that require precise control of output voltage and frequency.

Conclusion:
The single-phase mid-point type cycloconverter uses two SCRs in total. These SCRs control the power flow and generate the desired output waveform. This configuration allows for variable frequency and voltage control, making it suitable for various applications.